A conventional reproduction apparatus which is capable of reading and reproducing audio information and image information concurrently from a record medium where the audio information and the image information are recorded, is described, for example, in the following Patent Document 1 or Patent Document 2.
FIG. 3 is a block diagram, showing the configuration of the main part of a conventional optical-disk simultaneous reproduction apparatus 900. In an optical-disk medium 901, audio data and image data are recorded, and such data is read by an optical pick-up 915.
The optical pick-up 915 is attached, for example, to an optical head (not shown) which executes a scan on the optical-disk medium 901. In order to read necessary audio data and image data, it moves, together with the optical head, on the optical-disk medium 901.
In terms of the audio data and the image data read by the optical pick-up 915, an audio-and-image decision section 902 distinguishes between the audio data and the image data. The audio data distinguished by the audio-and-image decision section 902 is switched by an audio switch section 903. Then, it is alternately stored in an audio storage section 904 and an audio storage section 905. On the other hand, the image data distinguished by the audio-and-image decision section 902 is switched by an image switch section 908. Then, it is alternately sent to an image expansion section 909 and an image expansion section 912.
In the image expansion section 909 or the image expansion section 912, for example, the image data compressed in a compression format such as a JPEG is restored to the initial image data which can be displayed. Then, it is stored in an image storage section 910 or an image storage section 913.
The audio data stored in the audio storage section 904 or the audio storage section 905 is alternately switched by an audio switch section 906. Then, it is alternately outputted, respectively, by an audio output section 907. When the audio data is stored in the audio storage section 904 by the switch of the audio switch section 903, the audio data already stored in the audio storage section 905 by the switch of the audio switch section 906 is outputted from the audio output section 907.
In contrast, when the audio data is stored in the audio storage section 905 by the switch of the audio switch section 903, the audio data already stored in the audio storage section 904 by the switch of the audio switch section 906 is outputted from the audio output section 907. Through such a switch, the audio data is continuously outputted without a break from the audio output section 907.
Similarly, the image data stored in the image storage section 910 or the image storage section 913 is alternately switched by an image switch section 911. Then, it is alternately outputted, respectively, by an image output section 914. When the image data is stored in the image storage section 910 by the switch of the image switch section 908, the image data already stored in the image storage section 913 by the switch of the image switch section 911 is outputted from the image output section 914.
In contrast, when the image data is stored in the image storage section 913 by the switch of the image switch section 908, the image data already stored in the image storage section 910 by the switch of the image switch section 911 is outputted from the image output section 914. Through such a switch, the image data is also continuously outputted without a break from the image output section 914.
These image data and audio data are, for example, static-image contents and audio contents that explain these image contents which are recorded in the single optical-disk medium 901. Hence, they need to be concurrently reproduced so as to synchronize in exact timing. This requires that both the image data and the audio data be continuously reproduced without a break.
FIG. 4 is a timing chart, showing the reproduction at the normal time of the above described conventional optical-disk simultaneous reproduction apparatus 900.
The optical pick-up 915 seeks for reading audio data. In FIG. 4, this period of time is denoted by “T921”. After this, without specific notice, the period when each operation is executed is designated by “T” and the following numeral. This “T” and the following three-digit number indicates the period when each operation is executed and the period's length at the same time.
Next, the optical pick-up 915 moves to a required place on the optical-disk medium 901 in the seek (T921). Then, it reads the audio data (T922). At this time, the audio data read from the optical-disk medium 901 is simultaneously stored through the audio switch section 903 in the audio storage section 904 (T922).
The audio data stored in the audio storage section 904 is outputted via the audio switch section 906 from the audio output section 907 (T951). In the above described serial processing, the audio contents recorded in the optical-disk medium 901 are reproduced.
Sequentially, the optical pick-up 915 seeks to a necessary position for reading image data from the optical-disk medium 901 (T923). Next, the optical pick-up 915 moves to a required place on the optical-disk medium 901 in a seek (T923). Then, it reads the image data (T924). This time is also the period (T924) for which the read image data is simultaneously written through the image switch section 908 in the image expansion section 909.
In the image expansion section 909, the written image data is expanded (T929). Then, the expanded image data is stored in the image storage section 910. Herein, as described above, the expansion of image data means, for example, that the image data compressed in such a format as a JPEG is restored to the initial image data which can be displayed. The image data stored in the image storage section 910 is outputted via the image switch section 911 from the image output section 914 (T952). In the above described serial processing, the image contents recorded in the optical-disk medium 901 are reproduced.
After finishing reading the image data (T924), the optical pick-up 915 seeks to the position on the optical-disk medium 901 which is necessary for reading the next audio data (T925). Through this seek, the optical pick-up 915 moves to the position on the optical-disk medium 901 which is necessary for reading the next audio data. Then, it reads the next audio data from this optical-disk medium 901 (T926).
At this time, the audio data read from the optical-disk medium 901 is simultaneously stored via the audio switch section 903, this time, in the audio storage section 905 different from the preceding one (T926). In this way, the preparation is completed for outputting the audio data stored in the audio storage section 905 from the audio output section 907.
At this time, the reproduction of the preceding audio data stored in the audio storage section 904 is not yet completed. This produces a certain spare time (T941). After this spare time (T941) has elapsed, the audio data stored in the audio storage section 905 is outputted via the audio switch section 906 from the audio output section 907 (T953). This state is expressed by the following formula (1).T951−(T923+T924+T925+T926)=T941>0  (1)
The seek time (T923) for reading image data, the period (T924) for reading the image data, the seek period (T925) for reading the next audio data and the period (T926) for reading the next audio data are summed up. This total period is the period of time required from the time when the audio data stored in the audio storage section 904 is read to the time when the next audio data stored in the audio storage section 905 is read.
The period of time required from the time when the audio data stored in the audio storage section 904 is read to the time when the next audio data stored in the audio storage section 905 is read is subtracted from the period (T951) for reproducing the audio data stored in the audio storage section 904. This period is the spare time (T941). As long as this value is plus, the audio data can be normally reproduced continuously and without a break.
After the next audio data stored in the audio storage section 905 has been read (T926), the optical pick-up 915 seeks for reading the next image data (T927). Then, the optical pick-up 915 seeks to a necessary position for reading the next image data. Sequentially, it reads the next image data from the optical-disk medium 901 (T928).
The image data read from the optical-disk medium 901 by the optical pick-up 915 is written, this time, in the image expansion section 912 different from the preceding one, by the switching of the image switch section 908 (T928). The image data written in the image expansion section 912 is expanded in the image expansion section 912. Then, it is restored to the initial data format which can be displayed and is stored in the image storage section 913 (T930). In this way, the preparation is completed for outputting it from the image output section 914.
However, at this time, the reproduction of the preceding image data stored in the image storage section 910 is not yet completed (T952). Hence, also in terms of the image data's reproduction, a spare time (T942) is produced. After the reproduction of the preceding image data stored in the image storage section 910 has been completed (T952), the next image data stored in the image storage section 913 starts to be reproduced (T954).
As described so far, in terms of the storage sections for audio of the audio storage section 904 and the audio storage section 905 and the storage sections for images of the image storage section 910 and the image storage section 913, two sets are prepared, respectively. Then, switching is executed to each of them and is repeatedly used alternately. In addition, the audio data and the image data can be concurrently reproduced continuously and without a break, as long as each period when audio data and image data are written and read always has a spare period.
In this conventional optical-disk simultaneous reproduction apparatus 900, image data and audio data are reproduced in the following way. They are read, not concurrently in reality, but alternately from a different position on the optical-disk medium 901 by the optical pick-up 915.
In other words, the storage of audio data in the audio storage section 904 and the audio storage section 905 for audio-data storage, and the storage of image data in the image storage section 910 and the image storage section 913 for image-data storage, are alternately used. Thereby, it looks as if the audio data and the image data were concurrently read. This makes it possible to reproduce the audio data and the image data simultaneously and in parallel.
However, as can be seen from the above explanation, this processing can be executed only on the precondition that the spare time (T941) and the spare time (T942) can be secured. For example, the positions on the optical-disk medium 901 in which audio data and image data to be concurrently read are recorded may be away from each other, like the fact that one is located at its outer circumferential part and the other is located at the inner circumferential part. Or, even if they are not separate so far, when a seek error is made because of some cause or other and a seek retry is executed, the time taken for such a seek may be longer. In these cases, the above described spare time cannot be secured.
FIG. 5 and FIG. 6 show an example of this state. FIG. 5 is an illustration, showing the position in which audio data is recorded and the position in which image data is recorded in an optical-disk medium. As shown in FIG. 5, audio data is recorded in an inner circumferential part 901a of a record area (i.e., a hatched area of FIG. 5) of the optical-disk medium 901 and image data is recorded in an outer circumferential part 901b. This lengthens the seek time (T923 of FIG. 4) when the optical pick-up 915 moves from the recording position of audio data to the recording position of image data and the seek time (T925 of FIG. 4) when the optical pick-up 915 moves from the recording position of image data to the recording position of audio data. Hence, the spare time (T941 of FIG. 4) may not be secured.
FIG. 6 is a timing chart, showing the reproduction at an abnormal time of the above described conventional optical-disk simultaneous reproduction apparatus 900. The reproduction timing chart at an abnormal time in the conventional optical-disk simultaneous reproduction apparatus 900 shown in FIG. 6 is different from the reproduction timing chart at the normal time in the conventional optical-disk simultaneous reproduction apparatus 900 shown in FIG. 4, only in the following point. It is the seek time (T925) for the next audio-data reading which follows the image-data reading (T924).
In the reproduction timing chart at an abnormal time in the conventional optical-disk simultaneous reproduction apparatus 900 shown in FIG. 6, the next seek time (T925) for reading the audio data is longer. Thus, before the next audio-data reading is completed (T926), the preceding audio-data reproduction period (T951) comes to an end. This produces a period of time (T943) for which the audio data is broken. This state is expressed by the following formula (2).T951−(T923+T924+T925+T926)=−T943<0  (2)
The seek time (T923) for reading image data, the period (T924) for reading the image data, the next seek period (T925) for reading the audio data and the period (T926) for reading the next audio data are summed up. This total period is the period of time required from the time when the audio data stored in the audio storage section 904 is read to the time when the next audio data stored in the audio storage section 905 is read.
The period of time required from the time when the audio data stored in the audio storage section 904 is read to the time when the next audio data stored in the audio storage section 905 is read is subtracted from the period (T951) for reproducing the audio data stored in the audio storage section 904. This period is the spare time (T943). At this time when the abnormality takes place, the seek period (T925) is too long, thus making this value minus.
As a result, the audio data cannot be reproduced continuously and without a break. This produces the period of time (T943) for which the audio data is broken. As one of the measures to evade this situation, it can be considered that the storage capacity is increased of the audio storage section 904 and the audio storage section 905 for audio-data storage and the image storage section 910 and the image storage section 913 for image-data storage.
However, a storage capacity always needs to be secured in advance which is large enough to guarantee that audio data is certainly concurrently reproduced with its audio unbroken. In order to do this, a storing means with a great capacity which is not used in an ordinary condition always has to be prepared for an abnormal occasion. It is unclear when such an abnormal occasion will occur, and thus, this measure is extremely inefficient.
Patent Document 1: Japanese Patent Laid-Open No. 11-238318 specification
Patent Document 2: published Japanese translation of PCT international publication for patent applications No. 2001-507471 specification